Nonoperative management of blunt splenic injury is the treatment of choice in hemodynamically stable patients. Detection of vascular injury by multidetector CT (MDCT) is the most significant factor predicting the need for endovascular treatment. This study evaluated the timing of the appearance of vascular lesions during angiography. Images from 20 patients embolized for pseudoaneurysms (PSA) were evaluated. Angiograms were reviewed for phase and timing of PSA. Admission MDCT was reviewed for injury grade and PSA. Initial MDCT evaluation indicated grade III and IV splenic injuries in 9 and 11 patients, respectively. PSA was seen on MDCT in 14/20 (70%) patients. Time from opacification of the aorta to vascular injury was 1.32 s for arterial phase injuries compared with 2.05 s for postcapillary injuries (P=0.097). Angiography demonstrated 15 vascular injuries during the arterial and 5 in the venous phase. Of injuries seen during arterial phase angiography, 10/15 (66%) were identified on MDCT. Of the five injuries that exhibited postcapillary-phase findings, 4/5 (80%) demonstrated PSA (P=0.5). Vascular lesions are a better indicator of subsequent clinical deterioration than splenic injury grade. PSAs are more frequently seen in postcapillary vascular injuries than arterial phase lesions with the current timing of MDCT. In a subset of patients in whom splenic injury grades III and IV warrant angiography, PSAs are not initially demonstrated on MDCT. Therefore, alteration of MDCT timing parameters to better correlate with arterial phase angiography may improve initial diagnosis of vascular injury.